Fix off-by-one errors in caret position application

* src/gtkutil.c (xg_im_context_preedit_changed):
* src/xfns.c (xic_preedit_caret_callback):
(xic_preedit_draw_callback): Constrain caret position to
SCHARS (arg) - 1.

2 files changed, 18 insertions, 15 deletions

diff --git a/src/gtkutil.c b/src/gtkutil.c
index c47386dae00..8eab6ee723d 100644
--- a/src/gtkutil.c
+++ b/src/gtkutil.c
@@ -6090,11 +6090,12 @@ xg_im_context_preedit_changed (GtkIMContext *imc, gpointer user_data)
   inev.kind = PREEDIT_TEXT_EVENT;
   inev.arg = build_string_from_utf8 (str);
 
-  Fput_text_property (make_fixnum (min (SCHARS (inev.arg),
-                                        max (0, cursor))),
-                      make_fixnum (min (SCHARS (inev.arg),
-                                        max (0, cursor) + 1)),
-                      Qcursor, Qt, inev.arg);
+  if (SCHARS (inev.arg))
+    Fput_text_property (make_fixnum (min (SCHARS (inev.arg) - 1,
+                                          max (0, cursor))),
+                        make_fixnum (min (SCHARS (inev.arg),
+                                          max (0, cursor) + 1)),
+                        Qcursor, Qt, inev.arg);
 
   kbd_buffer_store_event (&inev);
 
diff --git a/src/xfns.c b/src/xfns.c
index 7540816416d..9cf6f528198 100644
--- a/src/xfns.c
+++ b/src/xfns.c
@@ -2973,11 +2973,12 @@ xic_preedit_caret_callback (XIC xic, XPointer client_data,
           ie.arg = make_string_from_utf8 (output->preedit_chars,
                                           output->preedit_size);
 
-          Fput_text_property (make_fixnum (min (SCHARS (ie.arg),
-                                                max (0, output->preedit_caret))),
-                              make_fixnum (max (SCHARS (ie.arg),
-                                                max (0, output->preedit_caret) + 1)),
-                              Qcursor, Qt, ie.arg);
+          if (SCHARS (ie.arg))
+            Fput_text_property (make_fixnum (min (SCHARS (ie.arg) - 1,
+                                                  max (0, output->preedit_caret))),
+                                make_fixnum (max (SCHARS (ie.arg),
+                                                  max (0, output->preedit_caret) + 1)),
+                                Qcursor, Qt, ie.arg);
 
           XSETINT (ie.x, 0);
           XSETINT (ie.y, 0);
@@ -3196,11 +3197,12 @@ xic_preedit_draw_callback (XIC xic, XPointer client_data,
       ie.arg = make_string_from_utf8 (output->preedit_chars,
                                       output->preedit_size);
 
-      Fput_text_property (make_fixnum (min (SCHARS (ie.arg),
-                                            max (0, output->preedit_caret))),
-                          make_fixnum (min (SCHARS (ie.arg),
-                                            max (0, output->preedit_caret) + 1)),
-                          Qcursor, Qt, ie.arg);
+      if (SCHARS (ie.arg))
+        Fput_text_property (make_fixnum (min (SCHARS (ie.arg) - 1,
+                                              max (0, output->preedit_caret))),
+                            make_fixnum (min (SCHARS (ie.arg),
+                                              max (0, output->preedit_caret) + 1)),
+                            Qcursor, Qt, ie.arg);
 
       XSETINT (ie.x, 0);
       XSETINT (ie.y, 0);